1. Field of the Invention
This invention relates to a device and to a method. More specifically, this invention is directed to a self-contained device for directing a fluid stream containing particulate matter against a surface to abrade, etch, erase, cut, penetrate, smooth, clean, polish and harden the surface. In one of the preferred embodiments of tile invention, the particulate matter is contained within the device, and a carrier fluid, under pressure, introduced therein to produce a fluid stream that can be delivered to a target surface. The device can be powered and/or energized by a source of compressed gas which is coupled to the device through a fixture designed for that purpose. The invention also includes a method for delivery of a particle stream, under pressure, to a target surface; and, to the selective modification of the target surface depending upon the hardness of tile particle, the velocity of impact and the extent of the exposure of the target surface to the particle stream.
2. Description of the Prior Art
The use of abrasives to modify tile surface of an object, (e.g., clean, polish, etch, etc.) is common practice in a variety of environments and professions. Typically such abrasive can take the form of a paste or free-flowing powder, and delivered to the surface of an object either manually, or through the use of a mechanical implement, or suspended in fluid (gas or liquid).
In the dental profession abrasives can be used to clean teeth and in the preparation of the dentition for bonding with various enamels and/or hardening agents. Typically the abrasive is delivered to the surface of the teeth by means of a carrier fluid stream (e.g., air or inert gas) containing a particulate abrasive. The object of such treatment is to remove foreign material, roughen or etch the surface to enhance bonding quality, or to dull an unsightly shine. As the gas and particulate matter impact the target material under pressure, the abrasive nature of the particles progressively causes layers of the target material to sheer one at a time. This process of controlled removal of material from the surface of the teeth is known as "etching".
Typically devices used in the delivery of the carrier fluid stream (e.g., air or inert gas) containing a particulate abrasive have resembled a sand blaster. More specifically, the generation of an abrasive fluid steam is accomplished by the placement of an abrasive in a reservoir and the drawing of the abrasive from the reservoir, under negative pressure, into an accelerated air or gas stream. The source of the accelerated air or gas stream) is typically a pressurized gas supplied from a compressor or tank.
In operation of the foregoing devices, the particle stream is directed through a channel of a nozzle (or delivery port) having a precise channel dimension and geometry. Typically this nozzle is constructed of metal or comparable durable material. As is appreciated, the precise delivery of the particle stream requires that the channel dimensions and geometry be maintained. Unfortunately, as the abrasive stream passes through the channel of the nozzle of the device, the inside diameter of the channel is worn (and the original tolerances altered), thereby causing a loss of precision, which ultimately requires the nozzle's replacement or replacement of the entire device. Additional maintenance is also required where, during the course of use, the device is exposed to debris or bacteria and thus must be cleaned prior to re-use. Because of the foregoing demands and constraints, such devices are typically expensive and thus are generally not readily discarded, even when in need of relatively extensive repair or refurbishing. Since such devices are not generally disposable, individuals must be skilled to maintain, clean, refill and reassemble them. This presents an opportunity for unit malfunction from contamination of the abrasive material, and by the reloading of the device with inappropriate and even dangerous particulate material.
Examples of these prior devices include that described in Fernwood, U.S. Pat. No. 4,941,298, issued on Jul. 17, 1990. Fernwood discloses a rear-reservoir micro sandblaster which includes a hollow tubular handle with a nozzle at one end for dispensing a mixture of a solid material and a gaseous medium, and a compressed air and solid particulate material-receiving member at the other end of the handle. The nozzle section of the apparatus contains a mixing chamber where a vacuum is created by the flowing pressurized gaseous medium, drawing solid material into the chamber from a rear reservoir Problems with Fernwood are that it is too costly to be disposable; it draws particulate matter from a container using a vacuum rather than by more efficient blow-through (turbulent or vortex) mixing of this gas as per the subject invention, and is thus very sensitive to variations in material and gas moisture levels, and requires an unclogging mechanisms, Fernwood also operates at relatively high pressures, 80-100 psi, requiring a special tap into the air lines and limiting the range of operational pressures. In addition, the Fernwood device suffers from one or more of the following perceived deficiencies:
requires special training to set up and use, PA1 cannot deliver varying sizes of particles, PA1 is contaminated after every use, and PA1 is not cost-effective and cannot be completely sterilized between use.
The apparatus disclosed in the Microetcher.TM. brochure (available from [insert company and address]) is similar to the Fernwood device in that it suffers from most, if not all, of the same perceived deficiencies. Other products available from various manufacturers, are similarly limited, and/or otherwise attempt to differentiate themselves from their competition by offering "improvements" relative to ease of cleaning and/or sterilization, e.g., Handiblaster.TM., available from Mirage/Chameleon Dental Products, Inc., of [insert address]; and Microetcher II.TM., available from [insert supplier, address].